Short retention times of stomach temperature loggers in free-living seabirds: is there hope in the spring?

Stomach temperature loggers have proved useful for the study of feeding activity in free-living seabirds, but their usage has been restricted because they are frequently dislodged and lost during the seabirds' regular regurgitation of indigestible prey remains. In the present study we examine the incidence of spontaneous regurgitation (pellet production) in free-living seabirds, consider the effect this has on the likely retrieval of stomach temperature loggers and present a structural modification of the logger housings which leads to a much lower incidence of regurgitation. Systems were tested on albatrosses, cormorants, gannets and penguins. Received: 15 July 1997 / Accepted: 31 October 1997     

Simultaneous hermaphroditism in the marine shrimp Lysmata wurdemanni (Caridea: Hippolytidae): an undescribed sexual system in the decapod Crustacea

Simultaneous hermaphroditism with outcrossing, a previously unconfirmed sexual system in decapod crustaceans, is documented in the shrimp Lysmata wurdemanni (Gibbes), using time-lapse video observations on mating in pairs of “female-phase” (FP) individuals. Copulations between FPs resulted in successful spawning and development of embryos. However, female-phase hermaphrodites maintained in isolation were unable to self-fertilize spawned eggs. All smaller individuals possessed characters typical of caridean males, including male gonopores, appendices masculinae, ejaculatory ducts, and cincinnuli on the first pleopods. However, the gonad of these male-phase (MP) individuals was an ovotestis with an undeveloped ovarian portion. FPs, which spawn eggs and incubate embryos, also had male gonopores and an ovotestis terminating in ejaculatory ducts containing sperm. In FPs, male pleopod characters were absent or reduced, and a female incubatory character, expanded pleopod flanges, showed a greater relative size. Smaller size classes of the population were composed only of MPs while larger size classes consisted of both MPs and FPs. “Transitionals,” individuals with MP characters but an ovotestis containing vitellogenic oocytes, were rare and overlapped completely in size with FP and larger MP individuals. It is suggested that not all MPs transform into FP hermaphrodites. Social interactions may mediate MP change into FP hermaphrodites in L. wurdemanni. The social system of L. wurdemanni and other Lysmata spp. may determine the exact form of the sexual system in these species. Received: 26 October 1997 / Accepted: 21 April 1998     

Recovery of benthic communities at Macquarie Island (sub-Antarctic) following a small oil spill

Intertidal communities at Macquarie Island (sub-Antarctic) were re-evaluated seven years after a small oil spill resulting from the grounding of the “Nella Dan”, and six years after the first assessment of biological impact. Sampling was conducted to evaluate community structure in three zones of the exposed rocky shore (upper red, kelp, and lower red) and in samples of Durvillaea antarctica holdfasts. There were no significant differences between the community structure in oiled and control locations in any of the three shore zones, but holdfast macrofaunal communities at oiled sites still showed evidence of impact. Holdfast community-structure in samples from heavily oiled sites showed moderate levels of recovery, with increased abundances of species which were considered sensitive to the oiling in the first post-impact studies and decreased abundances of opportunistic polychaete and oligochaete worms. In contrast, samples collected from the moderately oiled location at Secluded Bay showed little evidence of recovery. Holdfasts at this site were filled with sediment containing traces of diesel oil, and the macrofaunal community was dominated by opportunistic worms. This study clearly indicates that even small incidents of anthropogenic perturbation can have long-lasting consequences for marine communities at Macquarie Island. Received: 23 July 1997 / Accepted: 5 February 1998     

Effects of Trichodesmium spp. blooms on penaeid prawn larvae

The effects of blooms of the cyanobacterium Trichodesmium spp. on penaeid prawn larvae were examined using in situ and laboratory rearing experiments and plankton surveys in Albatross Bay, Gulf of Carpentaria, Australia. The in situ experiments demonstrated that, during a bloom of Trichodesmium spp., larvae of the prawn Penaeus merguiensis did not develop beyond the first protozoea stage, and survival was low compared with times when diatoms were dominant in the same study area. Laboratory experiments confirmed the in situ results. None of the prawn larvae fed Trichodesmium sp. in laboratory experiments developed beyond the first protozoeal stage. In contrast, 94% of prawn larvae fed the green flagellate Tetraselmis suecica successfully developed to the second protozoea stage. Electron microscopy of larvae gut-contents revealed that Trichodesmium spp. were ingested by larvae but were of no nutritional value, resulting in starvation. A 7 yr plankton survey, from 1985 to 1992, showed that minimum abundance of prawn larvae occurs during the annual summer blooms of Trichodesmium spp. and that maximum abundance of prawn larvae generally occurs just after the bloom. There was a negative correlation between the abundance of larvae and the abundance of Trichodesmium at individual sites, one offshore and one inshore, indicating that the blooms affect the survival of larvae. We conclude that variations in both timing and magnitude of Trichodesmium blooms are important determinants of prawn larvae abundance in Albatross Bay. Received: 28 April 1997 / Accepted: 2 April 1998     

A correction to: biological and oceanographic insights from larval labrid (Pisces: Labridae) identification using mtDNA sequences

Previously published mtDNA cytochrome b sequences for Xyrichtys novacula (Linnaeus) and two morphologically distinct types of Xyrichtys larvae (Pisces: Labridae) included human cytochrome b sequence, presumably due to sample contamination and/or poor preservation of sample DNA. Those sequences had been used to identify the two types of Xyrichtys larvae as X. novacula, but owing to the contamination, the identifications are invalid. Fresh specimens were collected: X.␣martinicensis (Cuvier and Valenciennes), X. novacula, X. splendens (Castelnau), and Xyrichtys sp. larvae of each of the two morphotypes (dorsal-forward eye and ventral-forward eye). The cytochrome b fragment was amplified from each specimen using the polymerase chain reaction. Comparison of the sequences with human cytochrome b sequence confirmed that the new sequences were not contaminated. The interspecific differences in Xyrichtys sequences were less than previously reported, but still greater than observed in many fish genera. Distance and parsimony analyses indicated that X. novacula and X. martinicensis were more closely related to each other than to X. splendens. This conclusion differs from our previous conclusion that X. martinicensis and X. splendens were more closely related to each other than to X. novacula. Distance and parsimony analyses also demonstrated that both larval morphotypes were X. novacula and, thus, our previous conclusions regarding larval ecology and oceanographic transport remain unchanged. Received: 12 March 1997 / Accepted: 24 October 1997     

Factors influencing food choice by the seaweed-eating marine snail Norrisianorrisi (Trochidae)

Through two-choice gustatory experiments, a␣preference hierarchy was established␣for␣the␣herbivorous gastropod Norrisianorrisi Sowerby, with laminarialean kelps preferred over all other seaweeds. Among the kelps, laminae of Macrocystispyrifera were slightly preferred over Egregiamenziesii, and both were strongly preferred over sporophylls of Eiseniaarborea. E.arborea, the least preferred kelp, was consistently chosen over other algae common in the snail's habitat (Halidrysdioica, Dictyotaflabellata, and Pterocladiacapillacea) and over seaweeds believed to be edible and palatable based on their morphology, structure, and secondary chemistry (Endarachnebinghamiae, Mazzaellaflaccida, and Ulvalobata). The morphologies and structural toughness of tested seaweeds varied significantly as did their nutritional (% carbon, % nitrogen, C:N ratio, and % ash) contents and phlorotannin concentrations; however, snails preferred to feed on kelps regardless of nutritional content, toughness or phlorotannin concentration; and among kelps preferred to feed on the least tough species (based on penetrometer measurements), which also were those containing the lowest phlorotannin concentrations. Preference for kelp was not upheld in experiments using agarose thalli to which freeze-dried powder, of either the kelp Eiseniaarborea or non-kelp Endarachnebinghamiae was added, suggesting the destruction of attractant chemicals during the making of the artificial foods. Our data suggest that the preference of N. norrisi for kelps over other potentially edible and palatable seaweeds may not be related to nutritional content, but instead may have evolved in response to factors such as availability, habitat provision, or refuge from predation. Received: 27 September 1996 / Accepted: 7 October 1997     

Settlement-competency periods of larvae of three species of scleractinian corals

The pattern of settlement over time of three broadcast spawning coral species (Cyphastrea serailia, Acanthastrea lordhowensis, and Goniastrea australensis) from the Solitary Islands (30°00′S; 153°20′E) was studied in 1995 and 1996 in order to determine the maximum length of time these larvae could remain in the water column and still retain the ability to settle and metamorphose. Larvae were maintained in aquaria and the number which had settled on biologically-conditioned tile pairs was monitored every 5 to 10 d. While the majority of larvae settled quickly after becoming competent, some larvae survived and settled for extended periods after spawning. Competency periods ranged from 26 d for C. serailia to 56 d for G. australensis and 78 d for A. lordhowensis. These data greatly extend the known competency periods for larvae of broadcast-spawning corals and indicate the potential for transport of broadcast-spawned coral larvae over large distances. Medium to long-distance larval dispersal of the species studied provides a mechanism for their widespread distribution in subtropical regions, on reefs which are often widely spaced and relatively isolated. Received: 27 May 1997 / Accepted: 27 November 1997     

Karyotypic characterization of the great sturgeon, Huso huso, by multiple staining techniques and fluorescent in situ hybridization

A karyotype analysis by several staining techniques was carried out on the great sturgeon, Huso huso (Linnaeus, 1758). The karyotype (2n = 118 ± 2) was composed of 42 pairs of meta-/submetacentric chromosomes and 17 pairs of acrocentrics/microchromosomes. Constitutive heterochromatin was mainly located at the centromeric regions of the acrocentric chromosomes. The biarmed chromosomes showed weak C-bands. Fluorescent staining with GC-specific chromomycin A₃ showed clearly recognizable fluorescent regions, whereas a more uniform base composition was revealed by the AT-specific 4,6-diamidino-2 phenylindole. After Ag-staining, nucleolar organizer regions could be observed on the short arms of two medium-sized submetacentrics and on two acrocentrics. Digoxigenated 28S and 5S rDNA probes, prepared from Acipenser naccarii DNA and hybridized to metaphase chromosomes, showed signals on six and two chromosomes, respectively. The telomeric sequence (TTAGGG) _n detected by FISH was located at both ends of each chromosome. Results are discussed in relation to karyotype organization and evolution in sturgeons. Received: 1 April 1998 / Accepted: 21 July 1998     

Effects of UV radiation of different wavebands on pigmentation, 15N-ammonium uptake, amino acid pools and adenylate contents of marine diatoms

Three marine diatoms Lauderia annulata Cleve, Odontella sinensis (Greville) Grunow and Thalassiosira rotula Meunier were exposed to ultraviolet (UV) radiation of different wavebands under controlled laboratory conditions (0.035 vol% CO₂, 18 °C). Several changes in the patterns of pigments in these organisms were seen depending on the waveband of UV radiation and species examined. UV-B and UV-B plus UV-A radiation led to a reduction in the overall pigment content of all three diatoms. The uptake of ¹⁵N-ammonium was less affected by 5-h UV-A (WG 320) but significantly reduced after UV-B and UV-B plus UV-A exposure. The pattern of free amino acid pools varied depending on the applied UV wavebands and the tested diatom. The main protein-bound amino acids of T. rotula decreased after 5-h UV irradiance except leucine. Contents of adenosine 5′-mono-, di-, and triphosphate (AMP, ADP and ATP) were affected differently by UV radiation; ATP values increased at the end of UV-B and UV-B plus UV-A exposure. These results have been discussed with reference to the impact of the different UV sources and the influence on the nitrogen metabolism in connection to pigments and supply with energy. Received: 13 May 1997 / Accepted: 11 October 1997